MINILAB 14.2 What do bases do?
Bases can be as reactive as some acids and just as
dangerous. Test the reactivities of three bases with
several common substances, and develop an operational definition for basic
solutions. Measure the pH by using universal indicator and a pH meter.
PURPOSE: TO TEST
THE REACTIVITIES OF THREE BASES AND TO DEVELOP AN OPERATIONAL DEFINITION FOR BASIC
SOLUTIONS.
HYPOTHESIS:
MATERIALS: Lime (Ca(OH)2), lye (NaOH), potash (KOH), (3)12-well microplate,
litmus paper, phenolphthalein indicator
solution, litmus indicator solution, hair, pieces of zinc, oil or fat, egg
white, UNIVERSAL INDICATOR, pH METER,
apron and goggles
PROCEDURE:
1. Wear an apron and goggles.
2. Add 10 drops of 1M Lime (Ca(OH)2), to wells 1-6 of a
clean, 12-well microplate. In the same manner, add 10
drops of 1M lye (NaOH), to a second microplate wells 1-6 and 10 drops of 1M potash (KOH),
to a third microplate wells 1-6.
**Don’t forget to record your observations on the data table for each
test.**
3. Dip red litmus paper into the
solutions in wells 1 for the three bases.
4. Add 2 drops of phenolphthalein indicator
solution to wells 2 for the three bases. This indicator turns from clear to pink
as the solutions become more basic.
5. In a similar manner, add a piece of
hair to wells 3 for the three bases; pieces of zinc to wells 4 for the three bases;
pieces of oil or fat to wells 5 for the three bases; and a small amount of egg
white to wells 6 for the three bases.
6. Dip universal test paper into the
solutions in wells 1 for the three bases. Determine the pH by matching with the
color chart.
7. Dip pH meter into the solutions
in wells 1 for the three bases.
8. Add 2 drops of litmus indicator
solution wells 1 for the three bases.
9. Dispose of all materials as directed
by your teacher. Rinse the microplates with tap water, then distilled water.
OBSERVATIONS
|
OTHER
REACTANT |
1 M Lime (Ca(OH)2) |
1 M lye (NaOH) |
1 M potash (KOH) |
|
LITMUS paper |
|
|
|
|
Phenolphthalein |
|
|
|
|
piece of hair |
|
|
|
|
ZINC |
|
|
|
|
oil or fat |
|
|
|
|
EGG WHITE |
|
|
|
|
UNIVERSAL INDICATOR |
|
|
|
|
pH METER |
|
|
|
|
LITMUS solution |
|
|
|
ANALYSIS
1. Summarize the reactions of the three bases with the
substances you tested. This summary constitutes an operational definition of an base.
2. Which base, although it had the same molar
concentration as the other bases, reacted more noticeably? Explain this behavior.